html, body {
  margin:0;
  padding:0;
  width:100%;
  height:100%;
}
#content {
  background-color: #ccc;
  position: relative;
  min-height: 100%;
}
* html #content {
  height: 100%;
}
#footer {
  background-color: #fff;
  position: relative;
  margin-top: -2.5em;
  height: 2.5em;
}